1. Field of the Invention
The present invention generally relates to a drive train for a motor vehicle, and more particularly relates to an improved high temperature slip spline boot for use on a prop shaft of a vehicle.
2. Description of Related Art
There are generally four main types of automotive drive line systems. More specifically, there is a full time front wheel drive system, a full time rear wheel drive system, a part time four wheel drive system and an all wheel drive system. Most commonly, the systems are distinguished by the delivery of power to different combinations of drive wheels, i.e., front drive wheels, rear drive wheels or some combination thereof. In addition to delivering power to a particular combination of drive wheels, both drive systems permit the respectively driven wheels to rotate at different speeds. For example, the outside wheels must rotate faster than the inside drive wheels and the front drive wheels must normally rotate faster than the rear drive wheels.
Drive line systems also include one or more constant velocity joints (CVJ). Such joints, which include by way of example and not limitation, a slip spline joint, a plunging tripod, a high speed fixed joint, along with any other known type are well known to those skilled in the art and are employed where a transmission of a constant velocity rotary motion is desired or acquired. A typical drive line system for a wheel rear or all wheel drive vehicle, for example, incorporates one or more constant velocity joints that connect a pair of front and rear propeller shafts (prop shafts) that transfer torque from a power take off unit to a rear drive line module or the like. Similarly the drive line system for a front wheel drive vehicle incorporates one or more constant velocity joints that transfer torque from a power take off unit to a rotary drive shaft.
These constant velocity joints are generally grease lubricated for life and sealed by a boot. The constant velocity joints are sealed in order to retain grease inside the joint keeping any contaminates and foreign matter, such as dirt and water, out of the joint. To achieve this protection, the constant velocity joint is usually enclosed at one end of the outer race by a sealing boot made of a rubber, thermoplastic, silicone, or other pliable material. The opposite end of the outer race is generally enclosed by either the opposite end of the boot, a dome or cap, or the internal geometry of the outer race of the constant velocity joint. The sealing and protection of the constant velocity joint is necessary because contamination of the joints may cause internal damage and destruction of the joint. Furthermore, once the inner chamber of the constant velocity joint is lubricated, it is generally lubricated for life.
During operation, the constant velocity joint creates internal pressure in the inner chamber of the joint. This is due to the joints high speed operation which create higher pressures and higher temperatures. These high speed high temperature environments may effect prior art boots stability thus reducing their effectiveness in protecting the joint they are sealing. Therefore, many prior art sealing boots generally have to be made of a higher stiffness material to operate properly in the high speed high temperature environment of the prop shafts. Many of the prior art high speed boots have reduced durability because the choice of stiffer materials create boots that were not capable of plunging, articulating and sealing properly in the extreme drive line conditions of a vehicle driveshaft. Also, the ingestion of any water or contaminates into a boot of a high speed high temperature joint via a distortion of the boot during operation or a rupture or tear of the boot, may impact that stability of the high temperature high speed boot and lead to contamination of the joint and thus reduce its durability and longevity. Such boot failures may even eventually result in a joint failure.
Therefore, there is a need in the art for an improved high speed high temperature boot for use with a constant velocity joint of a prop shaft in a vehicle.
Furthermore, there is the need in the art for a symmetrical boot design with precise length and angles to achieve an optimal boot for a high temperature high speed environment that will be stable in such an environment. There also is a need in the art for an improved split spline boot for use in the drive line of a vehicle.